Glass impeller for a blood pump

ABSTRACT

A blood pump includes an impeller assembly housing; and an impeller assembly disposed within the impeller assembly housing. The impeller assembly includes an impeller having a main body, at least one impeller blade extending outwardly therefrom, and a skirt disposed around at least a portion of the main body. At least a portion of the at least one impeller blade is disposed between the main body and an inner surface of the skirt.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 17/004,110, filed Aug. 27, 2020, which claimspriority to U.S. Provisional Application No. 62/894,010, filed Aug. 30,2019, which is herein incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to percutaneous circulatory supportdevices. More specifically, the disclosure relates to impellers used inpercutaneous circulatory support devices.

BACKGROUND

Percutaneous circulatory support devices such as blood pumps typicallyprovide circulatory support for up to approximately three weeks ofcontinuous use. Wear at bearing surfaces can limit the lifetime of thedevices. Additionally, heat generation and mechanical interactions withthe blood at the bearing and impeller-blade surface can lead tohemolysis, which can further lead to health complications such asanemia, requiring blood transfusions. Additionally, increased frictionat the blood-surface interface may require higher motor power tomaintain the pump output, which may warrant a bigger motor size.

SUMMARY

In an Example 1, a blood pump, comprising: an impeller assembly housing;and an impeller assembly disposed within the impeller assembly housing,the impeller assembly comprising an impeller having a main body, atleast one impeller blade extending outwardly therefrom, and a skirtdisposed around at least a portion of the main body, wherein at least aportion of the at least one impeller blade is disposed between the mainbody and an inner surface of the skirt.

In an Example 2, the blood pump of Example 1, wherein the at least oneimpeller blade is connected to the skirt.

In an Example 3, the blood pump of either of Examples 1 or 2, whereinthe impeller is one solid piece.

In an Example 4, the blood pump of any of Examples 1-3, wherein theimpeller is made of chemically strengthened glass.

In an Example 5, the blood pump of any of Examples 1-4, wherein theimpeller assembly is configured to rotate within the impeller assemblyhousing.

In an Example 6, the blood pump of Example 5, the skirt comprising anouter surface configured to be disposed adjacent an inner surface of theimpeller assembly housing.

In an Example 7, the blood pump of any of Examples 1-6, the skirt havinga proximal end and a distal end, the distal end having a distal outeredge, wherein the at least one impeller blade includes a leading edgethat is at least partially coplanar with at least a portion of thedistal outer edge.

In an Example 8, the blood pump of Example 7, wherein at least a portionof the leading edge is coplanar with the distal outer edge.

In an Example 9, the blood pump of either of Examples 7 or 8, whereinthe leading edge extends radially inward from an inner surface of theskirt to an outer surface of the main body.

In an Example 10, the blood pump of any of Examples 7-9, wherein a firstportion of the leading edge is coplanar with at least a portion of thedistal outer edge, and

wherein a second portion of the leading edge slopes axially toward theproximal end of the skirt.

In an Example 11, the blood pump of Example 10, the main body comprisinga distal end that is disposed proximal the distal outer edge.

In an Example 12, the blood pump of any of Examples 7-9, wherein theentire leading edge is coplanar with the entire distal outer edge.

In an Example 13, the blood pump of any of Examples 1-12, wherein awidth of distal end of the skirt is greater than a width of the proximalend of the skirt.

In an Example 14, the blood pump of any of Examples 1-13, wherein theimpeller assembly is maintained in place using only one bearingassembly, the one bearing assembly being disposed at a proximal end ofthe impeller assembly.

In an Example 15, an impeller fora blood pump, comprising: a main body;

-   -   at least one impeller blade extending outwardly therefrom; and a        skirt disposed around at least a portion of the main body,        wherein the impeller is made of glass.

In an Example 16, a blood pump, comprising: an impeller assemblyhousing; and an impeller assembly disposed within the impeller assemblyhousing, the impeller assembly comprising an impeller having a mainbody, at least one impeller blade extending outwardly therefrom, and askirt disposed around at least a portion of the main body, wherein atleast a portion of the at least one impeller blade is disposed betweenthe main body and an inner surface of the skirt.

In an Example 17, the blood pump of Example 16, wherein the at least oneimpeller blade is connected to the skirt.

In an Example 18, the blood pump of Example 16, wherein the impeller isone solid piece.

In an Example 19, the blood pump of Example 16, wherein the impeller ismade of chemically strengthened glass.

In an Example 20, the blood pump of Example 16, wherein the impellerassembly is configured to rotate within the impeller assembly housing.

In an Example 21, the blood pump of Example 20, the skirt comprising anouter surface configured to be disposed adjacent an inner surface of theimpeller assembly housing.

In an Example 22, the blood pump of Example 16, the skirt having aproximal end and a distal end, the distal end having a distal outeredge, wherein the at least one impeller blade includes a leading edgethat is at least partially coplanar with at least a portion of thedistal outer edge.

In an Example 23, the blood pump of Example 22, wherein at least aportion of the leading edge is coplanar with the distal outer edge.

In an Example 24, the blood pump of Example 22, wherein the leading edgeextends radially inward from an inner surface of the skirt to an outersurface of the main body.

In an Example 25, the blood pump of Example 22, wherein a first portionof the leading edge is coplanar with at least a portion of the distalouter edge, and wherein a second portion of the leading edge slopesaxially toward the proximal end of the skirt.

In an Example 26, the blood pump of Example 25, the main body comprisinga distal end that is disposed proximal the distal outer edge.

In an Example 27, the blood pump of Example 22, wherein the entireleading edge is coplanar with the entire distal outer edge.

In an Example 28, the blood pump of Example 16, wherein a width ofdistal end of the skirt is greater than a width of the proximal end ofthe skirt.

In an Example 29, the blood pump of Example 16, wherein the impellerassembly is maintained in place using only one bearing assembly, the onebearing assembly being disposed at a proximal end of the impellerassembly.

In an Example 30, an impeller for a blood pump, comprising: a main body;

-   -   at least one impeller blade extending outwardly therefrom; and a        skirt disposed around at least a portion of the main body,        wherein the impeller is made of glass.

In an Example 31, the impeller of Example 30, wherein the at least oneimpeller blade is connected to the skirt.

In an Example 32, the impeller of Example 30, wherein the impeller isone solid piece.

In an Example 33, the impeller of Example 30, the skirt having aproximal end and a distal end, the distal end having a distal outeredge, wherein the at least one impeller blade includes a leading edgethat is at least partially coplanar with at least a portion of thedistal outer edge.

In an Example 34, the impeller of Example 30, wherein the impellerassembly is maintained in place using only one bearing assembly, the onebearing assembly being disposed at a proximal end of the impellerassembly.

In an Example 35, a blood pump, comprising: an impeller assemblyhousing; and an impeller assembly disposed within the impeller assemblyhousing, the impeller assembly comprising an impeller having a mainbody, at least one impeller blade extending outwardly therefrom, and askirt disposed around at least a portion of the main body, wherein atleast a portion of the at least one impeller blade is disposed betweenthe main body and an inner surface of the skirt, wherein the impeller ismade of glass.

While multiple embodiments are disclosed, still other embodiments of thepresently disclosed subject matter will become apparent to those skilledin the art from the following detailed description, which shows anddescribes illustrative embodiments of the disclosed subject matter.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a cross-sectional side view of a portion of anillustrative percutaneous mechanical circulatory support device (alsoreferred to herein, interchangeably, as a “blood pump”), in accordancewith prior designs.

FIG. 2A depicts a perspective view of an illustrative percutaneousmechanical circulatory support device, in accordance with embodiments ofthe subject matter disclosed herein.

FIG. 2B depicts a cross-sectional end view of the circulatory supportdevice depicted in FIG. 2A, in accordance with embodiments of thesubject matter disclosed herein.

FIG. 3 is a perspective view of an illustrative impeller, in accordancewith embodiments of the subject matter disclosed herein.

FIG. 4 is a perspective view of another illustrative impeller, inaccordance with embodiments of the subject matter disclosed herein.

FIG. 5A is a perspective view depicting another illustrative impeller,in accordance with embodiments of the subject matter disclosed herein.

FIG. 5B is a schematic end view of the impeller depicted in FIG. 5A, inaccordance with embodiments of the subject matter disclosed herein.

FIG. 6A is a perspective view depicting another illustrative impeller,in accordance with embodiments of the subject matter disclosed herein.

FIG. 6B is a partially cut-away perspective view of the impellerdepicted in FIG. 6A, shown disposed within an impeller assembly housing,in accordance with embodiments of the subject matter disclosed herein.

While the disclosed subject matter is amenable to various modificationsand alternative forms, specific embodiments have been shown by way ofexample in the drawings and are described in detail below. Theintention, however, is not to limit the subject matter disclosed hereinto the particular embodiments described. On the contrary, the disclosureis intended to cover all modifications, equivalents, and alternativesfalling within the scope of the subject matter disclosed herein, and asdefined by the appended claims.

DETAILED DESCRIPTION

FIG. 1 depicts a cross-sectional side view of a portion of anillustrative percutaneous mechanical circulatory support device 100(also referred to herein, interchangeably, as a “blood pump”), inaccordance with prior designs. As shown in FIG. 1 , the circulatorysupport device 100 includes a motor 102 disposed within a motor housing104. The motor 102 is configured to drive an impeller assembly 106 toprovide a flow of blood through the device 100. The impeller assembly106 is disposed within an impeller assembly housing 108, which includesa number of outlet apertures 110 defined therein. According toembodiments, the motor housing 104 and the impeller assembly housing 108may be integrated with one another. In other embodiments, the motorhousing 104 and the impeller assembly housing 108 may be separatecomponents configured to be coupled together, either removeably orpermanently.

As shown in FIG. 1 , the impeller assembly 106 includes a drive shaft112 and an impeller 114 coupled thereto, where the drive shaft 112 isconfigured to rotate with the impeller 114. As shown, the drive shaft112 is at least partially disposed within the impeller 114. Inembodiments, the drive shaft 112 may be made of any number of differentrigid materials such as, for example, steel, titanium alloys, cobaltchromium alloys, nitinol, high-strength ceramics, and/or the like. Theimpeller assembly 106 further includes an impeller rotor 116 coupled to,and at least partially surrounding, the drive shaft 112. The impellerrotor 116 may be any type of magnetic rotor capable of being driven by astator (not shown) that is part of the motor 102. In this manner, as amagnetic field is applied to the impeller rotor 116 by the stator in themotor 102, the rotor 116 rotates, causing the drive shaft 112 andimpeller 114 to rotate.

As shown, the impeller assembly 106 is maintained in its orientation bythe drive shaft 112, which is retained, at a first end 118, by a first(proximal) bearing assembly 120 and, at a second end 122, by a second(distal) bearing assembly 124. According to embodiments, the firstbearing assembly 120 and the second bearing assembly 124 may includedifferent types of bearings. According to embodiments, the first bearingassembly 120 and/or the second bearing assembly 124 may includelubrication, while, in other embodiments, one and/or the other may notinclude lubrication. As the terms “proximal” and “distal” are usedherein, “proximal” refers to the general direction opposite that ofinsertion—that is, the direction in which one would travel along thedevice to exit the subject's body; whereas distal refers to the generaldirection of implantation—that is, the direction in which one wouldtravel along the device to reach the end of the device that isconfigured to advance into the subject's body.

The prior impeller is generally made out of PEEK using conventionalmachining and subsequent polishing. The impeller needs to be strong,precisely dimensioned and smooth to avoid damage to the blood cells.There are significant limitations regarding the freedom of designbecause of this manufacturing process. Although 3D printing might givemuch broader freedom regarding shapes, one has to realize that complexshapes will make polishing more difficult or even impossible. Theimpeller 114 is furthermore mounted in a metal housing 108. Studies ofthe flowlines though the prior pump have revealed that there is quite abit of shear force between the rotating fluid and the static inner wallof the housing 108.

Furthermore, as described above, the impeller 114 is supported by thetwo endpoints, allowing it to rotate. The proximal bearing 120dissipates both axial and radial force, while the distal bearing 124just holds the impeller 114 in radial position. Having the distalbearing 124 in place requires axial space for mounting and introducesflow resistance. Embodiments of the disclosure include a blood pumphaving only a proximal bearing (the distal bearing is not included).This may reduce flow resistance and facilitate shortening the overallconstruction of the blood pump, which may enable the device to betterfit within an arching aorta.

FIG. 2A depicts a cross-sectional side view of a portion of anillustrative percutaneous mechanical circulatory support device 200(also referred to herein, interchangeably, as a “blood pump”); and FIG.2B depicts a cross-sectional end view of the circulatory support device200 depicted in FIG. 2A, in accordance with embodiments of the subjectmatter disclosed herein. According to embodiments, a number of variouscomponents of the circulatory support device 200 may be the same as, orsimilar to, corresponding components of the circulatory support device100 depicted in FIG. 1 .

As shown in FIG. 2A, the circulatory support device 200 includes a motor202 disposed within a motor housing 204. The motor 202 is configured todrive an impeller assembly 206 to provide a flow of blood through thedevice 200. The impeller assembly 206 is disposed within an impellerassembly housing 208, which includes a number of outlet apertures 210defined therein. According to embodiments, the motor housing 204 and theimpeller assembly housing 208 may be integrated with one another. Inother embodiments, the motor housing 204 and the impeller assemblyhousing 208 may be separate components configured to be coupledtogether, either removeably or permanently.

A controller (not shown) is operably coupled to the motor 202 and isconfigured to control the motor 202. The controller may be disposedwithin the motor housing 204 in embodiments, or, in other embodiments,may be disposed outside the housing 204 (e.g., in a catheter handle,independent housing, etc.). In embodiments, the controller may includemultiple components, one or more of which may be disposed within thehousing 204. According to embodiments, the controller may be, include,or be included in one or more Field Programmable Gate Arrays (FPGAs),one or more Programmable Logic Devices (PLDs), one or more Complex PLDs(CPLDs), one or more custom Application Specific Integrated Circuits(ASICs), one or more dedicated processors (e.g., microprocessors), oneor more central processing units (CPUs), software, hardware, firmware,or any combination of these and/or other components. Although thecontroller is referred to herein in the singular, the controller may beimplemented in multiple instances, distributed across multiple computingdevices, instantiated within multiple virtual machines, and/or the like.

As shown in FIG. 2A, the impeller assembly 206 includes a drive shaft212 and an impeller 214 coupled thereto, where the drive shaft 212 isconfigured to rotate with the impeller 214. As shown, the drive shaft212 is at least partially disposed within the impeller 214. Inembodiments, the drive shaft 212 may be made of any number of differentrigid materials such as, for example, steel, titanium alloys, cobaltchromium alloys, nitinol, high-strength ceramics, and/or the like. Theimpeller assembly 206 further includes an impeller rotor 216 coupled to,and at least partially surrounding, the drive shaft 212. The impellerrotor 216 may be any type of magnetic rotor capable of being driven by astator (not shown) that is part of the motor 202. In this manner, as amagnetic field is applied to the impeller rotor 216 by the stator in themotor 202, the rotor 216 rotates, causing the drive shaft 212 andimpeller 214 to rotate. In embodiments, the impeller assembly 206 may beconfigured to be directly driven by the motor 202. That is, for example,instead of having a rotor/stator configuration, the motor 202 may beconfigured to cause the drive shaft 212 to rotate, which thereby causesthe impeller 214 to rotate.

As shown, the impeller assembly 206 is maintained in its orientation bythe drive shaft 212, which is retained, at a first end 218, by aproximal bearing assembly 220. According to embodiments, the bearingassembly 220 may include lubrication, and may be, or include, any numberof different types of bearings. In contrast to prior designs (e.g., asshown in FIG. 1 ), embodiments of the device 200 disclosed herein mayomit a distal bearing assembly that is independent of the impellerassembly 206. Instead, as shown, the impeller 214 includes a skirt 222disposed around at least a portion of a main body 224. One or moreimpeller blades 226 are connected to the skirt 222 and the main body 224and are disposed at least partially between the skirt 222 and the mainbody 224. According to embodiments, the skirt 222 may include an outersurface that is configured to be disposed adjacent an inner surface 230of the impeller assembly housing 208 such that the skirt 222 functionsas a bearing, maintaining the position of the impeller 214 within theimpeller assembly housing 208. In embodiments, since both surfaces (theblades and surrounding tubing (skirt)) are all rotating at the samespeed and in the same direction, there may be much less shear force onthe flow, thereby producing less damage to the blood.

According to embodiments, the impeller 214 may be made of glass such as,for example, by using selective laser etching to fashion the impeller214 all in one piece from a glass block. Selective laser-induced etching(SLE) is a two-step process to produce 3D structures in transparentmaterials (also known as ISLE: In-volume selective laser inducedetching—to distinguish our process from laser ablation). In a firststep, the transparent fused silica glass is modified internally by laserradiation to increase the chemical etchability locally. To prevent theformation of cracks in the brittle material, short pulse duration(fs-ps) and a small focal volume (a few μm3) may be used. The focus isscanned inside the glass to modify a 3D connected volume with contact tothe surface of the workpiece.

In a second step, the modified material is selectively removed by wetchemical etching resulting in the development of the 3D product. Theselectivity is the ratio of the etching rate of the modified materialand the etching rate of the untreated material. The selectivity in fusedsilica glass is larger than 500:1, resulting in long fine channels withsmall conicity. Therefore, by the SLE-technique, complex 3D cavities canbe produced, like micro fluidic structures and micro structures 3Dparts. According to embodiments, advantages of SLE are the largeprecision (˜1 μm), no debris, true 3D capability and the high processingspeed using micro scanners.

A prior polishing process for glass materials uses disc or point toolsand a polishing liquid, which is applied to the work piece. In thatprocess, large amounts of waste can arise. By means of laser polishing,glass surfaces can be polished without creating waste, independent ofthe surface form and with the same tool. In addition, the processingtime of laser polishing is smaller by a factor of up to 100 times. Itcan attain a surface roughness of quartz glass down to Root Mean Squareroughness (RMS)<5 nm (1×1 mm2 measuring field) and micro roughness downto RMS<0.4 nm (50×70 p m2 measuring field). Applications for laserpolishing of glass surfaces are, among others, lighting optics, forwhich the values currently achieved are sufficient. The process can beapplied to nearly all kinds of glass, whereas higher process speeds arereached for low-melting glasses. The very low roughness values comparedto the PEEK impeller designs (RMS of roughly 100 nm) results in a muchlower friction on the blood, hence a reduction in hemolysis.

In embodiments, impellers described herein may be made of chemicallystrengthened glass. Chemically strengthened glass is a type of glassthat has increased strength as a result of a post-production chemicalprocess. Chemically strengthened glass is typically six to eight timesthe strength of float glass. The glass is chemically strengthened by asurface finishing process. Glass is submersed in a bath containing apotassium salt (typically potassium nitrate) at 300° C. (572° F.). Thiscauses sodium ions in the glass surface to be replaced by potassium ionsfrom the bath solution. These potassium ions are larger than the sodiumions and therefore wedge into the gaps left by the smaller sodium ionswhen they migrate to the potassium nitrate solution. This replacement ofions causes the surface of the glass to be in a state of compression andthe core in compensating tension. The surface compression of chemicallystrengthened glass may reach up to 690 MPa.

The strengthening mechanism depends on the fact that the compressivestrength of glass is significantly higher than its tensile strength.With both surfaces of the glass already in compression, it takes acertain amount of bending before one of the surfaces can even go intotension. More bending is required to reach the tensile strength. Theother surface simply experiences more and more compressive stress. Butsince the compressive strength is so much larger, no compressive failureis experienced. There also exists a more advanced two-stage process formaking chemically strengthened glass, in which the glass article isfirst immersed in a sodium nitrate bath at 450° C. (842° F.), whichenriches the surface with sodium ions. This leaves more sodium ions onthe glass for the immersion in potassium nitrate to replace withpotassium ions. In this way, the use of a sodium nitrate bath increasesthe potential for surface compression in the finished article. Chemicalstrengthening results in a strengthening similar to toughened glass.However, the process does not use extreme variations of temperature andtherefore chemically strengthened glass has little or no bow or warp,optical distortion or strain pattern. This differs from toughened glass,in which slender pieces can be significantly bowed.

According to embodiments, by using aspects of the manufacturing processdescribed above to produce blood pump impellers made of glass, theimpellers may be designed to have any number of different shapes,optimized for hydrodynamic performance, and/or the like. Examples ofsome illustrative design concepts are described below with respect toFIG. 3 and FIG. 4 .

The illustrative circulatory support device 200 shown in FIGS. 2A and 2Bis not intended to suggest any limitation as to the scope of use orfunctionality of embodiments of the present disclosure. The illustrativecirculatory support device 200 also should not be interpreted as havingany dependency or requirement related to any single component orcombination of components illustrated therein. Additionally, variouscomponents depicted in FIGS. 2A and 2B may be, in embodiments,integrated with various ones of the other components depicted therein(and/or components not illustrated), all of which are considered to bewithin the ambit of the present disclosure.

FIG. 3 is a perspective view of an illustrative impeller 300, inaccordance with embodiments of the subject matter disclosed herein.According to embodiments, the impeller 300 may be made from glass suchas, for example, by using aspects of a manufacturing processes describedherein, and may be, or be similar to, the impeller 214 described. Asshown in FIG. 3 , the impeller 300 includes a main body 302 and a skirt304 disposed around at least a portion of the main body 302. A firstimpeller blade 306 and a second impeller blade 308 extend outwardly fromthe main body 302.

Embodiments of the impeller may incorporate as shown in FIG. 3 , atleast a portion of each of the two impeller blades 306 and 308 isdisposed between the main body 302 and an inner surface 310 of the skirt304. Each of the impeller blades 306 and 308 is connected to the skirt304. In embodiments, the impeller blades 306 and 308 may be connected tothe skirt 304 at various points. The skirt 304 also includes an outersurface 312 configured to be disposed adjacent an inner surface of animpeller assembly housing (not shown).

In the illustrated embodiments, the skirt 304 includes a cylinder havinga first (proximal) end 314 and a second (distal) end 316. The inner andouter surfaces 310 and 312 extend between the first and second ends 314and 316. In other embodiments, the skirt 304 may be tapered such that adiameter of the skirt at one end is larger than the diameter at theother end. For example, in embodiments, the diameter of the skirt 304may be greater at or near the distal end 316 than the diameter of theskirt 304 at or near the proximal end 314. In embodiments, the skirt maybe configured, as illustrated, to have a circular radial cross section,while, in other embodiments, the skirt 304 may be configured to have aradial cross section of any number of other shapes, so long as the shapeof the skirt does not prevent the skirt from rotating within an impellerhousing.

Each of the impeller blades 306 and 308 includes a leading edge 318,320, respectively. The leading edge 318 is the distal-most edge of theimpeller blade 306, and the leading edge 320 is the distal-most edge ofthe impeller blade 308. That is, the leading edges 318 and 320 are theedges of the impeller blades 306 and 308, respectively, that firstencounter blood as it flows into the device and across the impeller 300.As shown in FIG. 3 , the skirt 304 includes a proximal outer edge 322 atthe proximal end of the skirt 304, and a distal outer edge 324 at thedistal end 316 of the skirt 304. In the illustrated embodiments, theentire leading edge 318 of the first impeller blade 306 and the entireleading edge 320 of the second impeller blade 308 each are coplanar withthe entire distal outer edge 324 of the skirt 304. In embodiments, oneor more of the leading edges 318 and 320 may be at least partiallycoplanar with at least a portion of the distal outer edge 324 of theskirt 304.

That is, for example, any portion or portions of one or more of theleading edges 318 and 320 (and/or leading edges of other blades notdepicted) may be coplanar with one or more portions of the distal outeredge 324 of the skirt 304. Although the distal outer edge 324 of theskirt 304 is illustrated as being entirely within a single plane,embodiments may include a distal outer edge 324 that is curved in anynumber of configurations such that one or more portions of the outeredge lie in different planes. In other embodiments, one or more of theleading edges 318 and 320 may be connected to the distal outer edge 324,but not have any portion that is coplanar therewith. According toembodiments, one or more of the impeller blades 306 and 308 may connectto the skirt 304 at the distal outer edge 324 and/or any other locationon the skirt 304. The impeller blades 306 and 308 are each shown ashaving a width that is greater near the distal end 316 than the widthnear the proximal end 314, where the width is the distance between theouter surface 326 of the main body and a trailing edge 328 or 330 of theimpeller 306 or 308 respectively, in a direction normal to the outersurface 326. In embodiments, one or more of the impeller blades 306 and308 may be configured to have a greater width near the proximal end 314than near the distal end 316, in which case, for example, the impellerblades 306 and/or 308 may be connected to the skirt 304 at or near theproximal end 314. In embodiments, the trailing edge 328 and/or 330 maybe integrated with the leading edge 316 and/or 318, respectively.

In embodiments, the leading edge 318 of the impeller 306 extendsradially inward from a surface (e.g., the distal outer edge 324, theinner surface 310, etc.) of the skirt 304 to an outer surface 326 of themain body 302. Similarly, the leading edge 320 of the impeller 308extends radially inward from a surface of the skirt 304 to the outersurface 326 of the main body 302. In embodiments, the leading edgeand/or trailing edge of an impeller may be straight and/or curved. Thatis, for example, the leading edge and/or trailing edge of an impellerblade may be curved radially and/or axially to provide a hydrodynamicshape.

As shown in FIG. 3 , the main body may include a distal end 332 thatprotrudes axially in the distal direction beyond a plane of the distalouter edge 324 of the skirt 304. The distal end 332 may be rounded,flat, and/or the like. The distal end 332 may, in embodiments, becoplanar with a plane of the distal outer edge 324 of the skirt 304, or,in other embodiments, may be located proximal to one or more planes ofthe distal outer edge 324. For example, FIG. 4 is a perspective view ofanother illustrative impeller 400, in accordance with embodiments of thesubject matter disclosed herein. According to embodiments, the impeller400 may be made from glass such as, for example, by using aspects of amanufacturing processes described herein, and may include aspects thatare the same as, or similar to, corresponding aspects of the impeller300 depicted in FIG. 3 .

As shown in FIG. 4 , the impeller 400 includes a main body 402 and askirt 404 disposed around at least a portion of the main body 402. Afirst impeller blade 406 and a second impeller blade 408 extendoutwardly from the main body 402.

Embodiments may include any number of impeller blades such as, forexample, one impeller blade, two impeller blades, three impeller blades,four impeller blades, and/or any other number of impeller blades. Asshown in FIG. 4 , at least a portion of each of the two impeller blades406 and 408 is disposed between the main body 402 and an inner surface410 of the skirt 404. Each of the illustrated impeller blades 406 and408 is connected to the skirt 404 at one or more locations between aproximal end 412 of the skirt 404 and a distal end 414 of the skirt 404.

Each of the impeller blades 406 and 408 includes a leading edge 416,418, respectively. The leading edge 416 is the distal-most edge of theimpeller blade 406, and the leading edge 418 is the distal-most edge ofthe impeller blade 408. That is, the leading edges 416 and 418 are theedges of the impeller blades 406 and 408, respectively, that firstencounter blood as it flows into the device and across the impeller 400.As shown in FIG. 4 , the skirt 404 includes a proximal outer edge 420 atthe proximal end 412 of the skirt 404, and a distal outer edge 422 atthe distal end 414 of the skirt 404. In the illustrated embodiments, aportion 424 of the leading edge 416 of the first impeller blade 406 anda portion 426 of the leading edge 418 of the second impeller blade 408each are coplanar with the distal outer edge 422 of the skirt 404.

As shown in FIG. 4 , each leading edge 416 and 418 curves in a proximaldirection to a distal end 428 of the main body 402. The distal end 428is disposed proximal to the distal outer edge 422 of the skirt 404. Theleading edge 416 of the impeller 406 extends radially inward from asurface (e.g., the distal outer edge 422, the inner surface 410, etc.)of the skirt 404 to an outer surface 430 of the main body 402.Similarly, the leading edge 418 of the impeller 408 extends radiallyinward from a surface of the skirt 404 to the outer surface 430 of themain body 402.

Although the impeller 400 depicted in FIG. 4 includes two impellerblades, impellers made in accordance with embodiments of the subjectmatter disclosed herein may have more than two blades. In embodiments,an impeller may have three blades, four blades, five blades, six blades,and/or the like. FIG. 5A is a perspective view depicting anotherillustrative impeller 500, having four blades, in accordance withembodiments of the subject matter disclosed herein. FIG. 5B is aschematic end view of the impeller 500 depicted in FIG. 5A, inaccordance with embodiments of the subject matter disclosed herein.According to embodiments, the impeller 500 may be made from glass suchas, for example, by using aspects of a manufacturing processes describedherein, and may include aspects that are the same as, or similar to,corresponding aspects of the impeller 300 depicted in FIG. 3 and/or theimpeller 400 depicted in FIG. 4 .

As shown in FIG. 5A, the impeller 500 includes a main body 502 and askirt 504 disposed around at least a portion of the main body 502. Afirst impeller blade 506, a second impeller blade 508, a third impellerblade 510, and a fourth impeller blade 512 extend outwardly from themain body 502. As shown in FIG. 5A, at least a portion of each of thefour impeller blades 506, 508, 510, and 512 is disposed between the mainbody 502 and an inner surface 514 of the skirt 504. Each of theillustrated impeller blades 506, 508, 510, and 512 is connected to theskirt 504.

Each of the impeller blades 506, 508, 510, and 512 includes a leadingedge 516, 518, 520, and 522, respectively. The leading edges 516, 518,520, and 522 include the distal-most edges of the respective impellerblades 506, 508, 510, and 512. That is, the leading edges 516, 518, 520,and 522 are the edges of the impeller blades 506, 508, 510, and 512,respectively, that first encounter blood as it flows into the device andacross the impeller 500. As shown in FIG. 5A, the skirt 504 includes adistal outer edge 524 at the distal end 526 of the skirt 504. In theillustrated embodiments, a portion 528 of the leading edge 516 of thefirst impeller blade 506 and a portion 530 of the leading edge 518 ofthe second impeller blade 508 each are coplanar with the distal outeredge 524 of the skirt 504, while no portion of either of the distaledges 520 or 522 is coplanar with the distal outer edge 524 of the skirt504.

As shown in FIGS. 5A and 5B, the impeller blades 506, 508, 510, and 512may be configured such that the blades include more than one set ofblades, in which the blades of each set are axially symmetric with eachother, similarly shaped, and/or the like. For example, as shown, theimpeller 500 may include a first set of impeller blades that includesthe first blade 506 and the third blade 510, and a second set ofimpeller blades that includes the second blade 508 and the fourth blade512. As shown, the first blade 506 is axially symmetric to the thirdblade 510, and the second blade 508 is axially symmetric to the fourthblade 512, but none of the blades of the first set are axially symmetricto any of the blades in the second set. That is, each leading edge 516and 518 of the first set of impeller blades curves in an axiallysymmetric direction to the other. Similarly, each leading edge 520 and522 of the second set of impeller blades curves in an axially symmetricdirection to the other. In embodiments, sets of blades may include twoblades, three blades, four blades, and/or the like, and an impeller mayinclude any number of distinct sets of impeller blades.

Although each of the impellers 300, 400, and 500 depicted in FIGS. 3, 4, and 5A-5B, respectively, includes a main body through which a centralaxis (not shown) of the impeller passes, implementation of themanufacturing processes disclosed herein enable creation of impellershaving bodies of other configurations. For example, in embodiments, themain body may include a number of different portions or legs, only someof which intersect the central axis. In other embodiments, none of thelegs intersect the central axis. An example of such an embodiment isdepicted in FIGS. 6A and 6B.

FIG. 6A is a perspective view depicting another illustrative impeller600, in accordance with embodiments of the subject matter disclosedherein. FIG. 6B is a partially cut-away perspective view of the impeller600 depicted in FIG. 6A, shown disposed within an impeller assemblyhousing 602, in accordance with embodiments of the subject matterdisclosed herein. According to embodiments, the impeller 600 may be madefrom glass such as, for example, by using aspects of a manufacturingprocesses described herein, and may include aspects that are the sameas, or similar to, corresponding aspects of the impeller 300 depicted inFIG. 3 , the impeller 400 depicted in FIG. 4 , and/or the impeller 500depicted in FIGS. 5A and 5B.

As shown in FIG. 6A, the impeller 600 includes a main body 604 extendingbetween a base portion 606 and a skirt 608. The skirt 608 is disposedaround at least one impeller blade 610. As shown in FIG. 6A, the mainbody 604 includes three individual legs 612, 614, and 616, extendingindependently from the base portion 606 to the skirt 608, leaving acentral space around the central axis 618 open. In embodiments, the baseportion 606 may be a housing containing a rotor (magnet), and mayinclude, as shown, a curved distal surface 620 to facilitate blood flowradially away from the central axis 618. Although FIG. 6A shows oneblade 610 extending across the skirt perimeter, it will be understoodthat multiple blades may be positioned axially with respect to oneanother. Additionally, as shown in FIG. 6A, each of the three legs 612,614, and 616 is slightly curved inwards, though other designs may beimplemented in accordance with embodiments of the subject matterdisclosed herein. Further, as shown in FIG. 6B, the flow outlets 622 ofthe impeller assembly housing 602 may be positioned such that there isspace between the legs 612, 614, and 616 and the outlets 622.

The illustrative circulatory support devices 300 shown in FIG. 3, 400shown in FIG. 4, 500 shown in FIGS. 5A and 5B, and 600 shown in FIGS. 6Aand 6B are not intended to suggest any limitation as to the scope of useor functionality of embodiments of the present disclosure. Theillustrative circulatory support devices 300, 400, 500, and 600 alsoshould not be interpreted as having any dependency or requirementrelated to any single component or combination of components illustratedtherein. Additionally, various components depicted in FIGS. 3, 4, 5A,5B, 6A, and 6B may be, in embodiments, integrated with various ones ofthe other components depicted therein (and/or components notillustrated), all of which are considered to be within the ambit of thepresent disclosure.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentdisclosure. For example, while the embodiments described above refer toparticular features, the scope of this disclosure also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present disclosure is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

We claim:
 1. A method of manufacturing a glass impeller for a bloodpump, the method comprising: providing a block of a glass; modifying theglass by laser radiation; and selectively removing a portion of themodified glass by wet chemical etching to form the glass impeller. 2.The method of claim 1, wherein the glass is a chemically strengthenedglass.
 3. The method of claim 1, wherein the glass comprises a surfaceenriched with potassium ions.
 4. The method of claim 1, wherein theglass comprises a surface in a state of compression and a core in astate of tension.
 5. The method of claim 1, wherein the glass impellerhas a selectivity greater than 500:1.
 6. The method of claim 1, whereinthe glass impeller has a root mean square surface roughness of less than5 nm with a 1×1 mm² measuring field.
 7. The method of claim 1, whereinthe glass impeller has a root mean square micro roughness of less than0.4 nm with a 50×70 μ² measuring field.
 8. A method of manufacturing ablood pump, the method comprising: providing a block of a glass;modifying the glass by laser radiation; selectively removing a portionof the modified glass by wet chemical etching to form a glass impeller;and coupling the glass impeller to a drive shaft within a housing of theblood pump.
 9. The method of claim 8, wherein the glass is a chemicallystrengthened glass.
 10. The method of claim 8, wherein the glasscomprises a surface enriched with potassium ions.
 11. The method ofclaim 8, wherein the glass comprises a surface in a state of compressionand a core in a state of tension.
 12. The method of claim 8, wherein theglass impeller has a selectivity greater than 500:1.
 13. The method ofclaim 8, wherein the glass impeller has a root mean square surfaceroughness of less than 5 nm with a 1×1 mm² measuring field.
 14. Themethod of claim 8, wherein the glass impeller has a root mean squaremicro roughness of less than 0.4 nm with a 50×70 μ² measuring field.